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Seen from a distance, objects appear reduced and close
together, however far apart they be: within easy range, their
sizes and the distances that separate them are observed
correctly.
Distant objects show in this reduction because they must be drawn
together for vision and the light must be concentrated to suit
the size of the pupil; besides, as we are placed farther and
farther away from the material mass under observation, it is more
and more the bare form that reaches us, stripped, so to speak, of
magnitude as of all other quality.
Or it may be that we appreciate the magnitude of an object by
observing the salience and recession of its several parts, so
that to perceive its true size we must have it close at hand.
Or again, it may be that magnitude is known incidentally [as a
deduction] from the observation of colour. With an object at hand
we know how much space is covered by the colour; at a distance,
only that something is coloured, for the parts, quantitatively
distinct among themselves, do not give us the precise knowledge
of that quantity, the colours themselves reaching us only in a
blurred impression.
What wonder, then, if size be like sound- reduced when the form
reaches us but faintly- for in sound the hearing is concerned
only about the form; magnitude is not discerned except
incidentally.
Well, in hearing magnitude is known incidentally; but how? Touch
conveys a direct impression of a visible object; what gives us
the same direct impression of an object of hearing?
The magnitude of a sound is known not by actual quantity but by
degree of impact, by intensity- and this in no indirect
knowledge; the ear appreciates a certain degree of force, exactly
as the palate perceives by no indirect knowledge, a certain
degree of sweetness. But the true magnitude of a sound is its
extension; this the hearing may define to itself incidentally by
deduction from the degree of intensity but not to the point of
precision. The intensity is merely the definite effect at a
particular spot; the magnitude is a matter of totality, the sum
of space occupied.
Still the colours seen from a distance are faint; but they are
not small as the masses are.
True; but there is the common fact of diminution. There is colour
with its diminution, faintness; there is magnitude with its
diminution, smallness; and magnitude follows colour diminishing
stage by stage with it.
But, the phenomenon is more easily explained by the example of
things of wide variety. Take mountains dotted with houses, woods
and other land-marks; the observation of each detail gives us the
means of calculating, by the single objects noted, the total
extent covered: but, where no such detail of form reaches us, our
vision, which deals with detail, has not the means towards the
knowledge of the whole by measurement of any one clearly
discerned magnitude. This applies even to objects of vision close
at hand: where there is variety and the eye sweeps over all at
one glance so that the forms are not all caught, the total
appears the less in proportion to the detail which has escaped
the eye; observe each single point and then you can estimate the
volume precisely. Again, magnitudes of one colour and unbroken
form trick the sense of quantity: the vision can no longer
estimate by the particular; it slips away, not finding the
stand-by of the difference between part and part.
It was the detail that prevented a near object deceiving our
sense of magnitude: in the case of the distant object, because
the eye does not pass stage by stage through the stretch of
intervening space so as to note its forms, therefore it cannot
report the magnitude of that space.
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